The Collaborative International Dictionary of English v.0.48:
Fatuity \Fa*tu"i*ty\, n. [L. fatuitas, fr. fatuus foolish: cf. F. fatuit['e] Cf. Fatuous.] Weakness or imbecility of mind; stupidity. [1913 Webster] Those many forms of popular fatuity. --I Taylor. [1913 Webster]WordNet (r) 3.0 (2006):
fatuity n 1: a ludicrous folly; "the crowd laughed at the absurdity of the clown's behavior" [syn: absurdity, fatuity, fatuousness, silliness]